A nona-band dual-antenna system for mobile handsets

A nona-band dual-antenna system for mobile handset applications is proposed. The dual-antenna system consists of two symmetric antenna elements, a decoupling ground branch and a floating structure. The antenna element incorporates a driven branch and a parasitic ground branch, generating a couple of resonant modes. A decoupling ground branch is adopted to reduce the mutual coupling in the lower band and improve the impedance matching in the higher band. To enhance the bandwidth of both the lower and higher bands and reduce the mutual coupling around the lower limit frequency of the higher band, a floating structure is added. The measured results show that the-6 dB common impedance bandwidth of the fabricated antenna prototype is 276 MHz (692~968 MHz) and 1 110 MHz (1 636~2 746 MHz), covering the LTE700/2300/2500, GSM850/900, DCS/PCS/UMTS and 2.4-GHz WLAN bands, with the mutual coupling lower than -10 dB and -13.7 dB in the lower and higher bands, respectively. Based on the measured three dimensional radiation patterns, the envelop correlation coefficient, the mean effective gain and the diversity gain are calculated. The calculated results show that a good diversity performance is achieved for the proposed dual-antenna system.